Generally, an engine torque reduction control is performed to reduce shift shock of an automatic transmission of a vehicle.
Conventionally, the prior engine torque reduction (ETR) control is performed simply during an upshift or a downshift. For example, during an upshift, for a simple sequential shift, the engine torque reduction control is performed for a predetermined time, if torque and throttle valve opening position at an instance of a shift begin (SB) point after a shift start (SS) point are greater than predetermined values.
Therefore, in the prior art, the engine torque reduction control is not performed during a shift such as a partial power-on lift-foot-up (LFU) shift during a kickdown shift or a kickdown shift during a lift-foot-up shift, or during a shift in which a control range is changed. In addition, in the prior art, the engine torque reduction control is not performed when a power-on upshift in which a power state is changed during a shift by an opening of a throttle valve while a lift-foot-up shift is being performed.
Furthermore, in a simple sequential shift, the engine torque reduction control is only performed depending on a torque or a throttle valve opening position at an instance of a shift begin SB point. Therefore, in the prior art, when a power-on lift-foot-up shift of a partial throttle opening occurs during a kickdown shift, or when a power-on upshift of a partial throttle opening occurs during a power off lift-foot-up shift, the engine torque reduction control is not performed, so that severe shift shocks may occur.
The information disclosed in this Background of the Invention section is only for enhancement of understanding of the background of the invention and should not be taken as an acknowledgement or any form of suggestion that this information forms the prior art that is already known to a person skilled in the art.